Mannesmann Rexroth Corporation

Rexroth-sigma

Bosch Rexroth D.s.i.

Michel Rivolier

Reiner Bartholomaus

Armin Steinhilber

The invention relates to a hydraulic distributor comprising a casing, a pressurized fluid inlet, a fluid return port, at least two working ports, a slide which is housed in the casing, a passage which is provided in the casing in order to connect the inlet with the working ports, adjustment means which are connected to a load detection line channel, a supply bridge which opens into the slide hole on either side of the inlet chamber, and two main check valves which are borne internally by the slide, The inventive distributor further comprises two secondary check valves which are mounted in the longitudinal channels upstream of the main check valve heads and which are connected to torque slits which open into the hole in which the slide moves.

Hydraulic distributor with torque slits

A hydraulic directional control valve with a regulating balance comprising a plunger which can be displaced in a housing (,3) under the action of a differential pressure (&Dgr;p) between the intake pressure (P) and the highest load pressure (LS), and which is designed to open, in proportion to this differential (&Dgr;p), a lateral orifice of the housing linked to a working orifice (A, B) of the directional control valve; the wall of the housing and/or the plunger is provided with a calibrated passage linking the intake of fluid at pressure (P) and the lateral orifice when the plunger is pushed back into an end position by the pressure (LS) exceeding the intake pressure (P); consequently, in spite of the excess value of the pressure (LS) intended to inhibit operation of the directional control valve, hydraulic fluid is delivered to the lateral orifice at a low rate and allows the hydraulic receiver controlled by the hydraulic directional control valve to be displaced at a low rate.

Hydraulic directional control valve

A pressure compensating hydraulic directional valve comprising: a body provided with a movable slide; a passage through the body for connecting a distribution chamber associated with the slide to working orifices, the distribution chamber being selectively connectable to an admission orifice by the slide when moved; a load sensing line channel combined with means for selecting the maximum pressure selected from the pressure in the channel and the pressure of the fluid in the valve; and pressure compensating means placed in the passage and responsive to the difference between the pressure in the passage and the pressure in the channel to generate a fixed pressure drop in the pressurized fluid flowing through the passage towards the working orifices, the pressure compensating means being combined with the maximum pressure selecting means in such a manner that if the pressure in the channel is greater than or equal to the pressure of the fluid from the slide, then no communication exists between the passage and the channel and the pressure in the channel retains its value, or else, if the pressure in the channel is less than the pressure of the fluid from the slide, communication is established between the passage and the channel, and the pressure in the channel becomes the same as the pressure of the pressurized fluid.

Hydraulic directional control valve combining pressure compensation and

A slide valve, in particular the piston of a switching valve, is actuated in both directions of adjustment by a pressure medium which acts on the annular face and/or the circular face of a regulating piston fixed one-sidedly to the slide valve. The equalization of the differing controlling forces, determined by the different sized surfaces of the regulating piston that are subjected to pressure, is achieved by means of a spring or by an hydraulic counterforce.

Growing community of inventors

L'Arbresle, France

Michel Rivolier